Hi
@KillerKthulu! You've experienced a Calcium deficiency, which can be related to a wrong pH range, lack of Cal+Mag in your feedings, or bad waterings (flooded roots). In soil, Calcium is best absorbed within the 6.2-7.0 pH range, so double check your pH-pen and make sure it's perfectly calibrated, and try to remain above the 6.2 value. I see that you have already solved this deficiency by adding CaliMagic, very well done, plants look 100% healthy! Let me know in the comments section if you need any further information, and happy growing mate! ๐